combine: More distribute_notes trouble (PR69737)

combine: More distribute_notes trouble (PR69737)

PR64682 is a problem in distribute_notes, where it has trouble putting
a REG_DEAD note for a reg that is set twice in the right spot.  My fix
for that did the wrong thing for PR69567.  And then my attempted fix
for that one made PR64682 fail again.

Instead, let's just lose the note in such complicated cases, like we
already do in certain similar cases.

	PR rtl-optimization/64682
	PR rtl-optimization/69567
	PR rtl-optimization/69737
	* combine.c (distribute_notes) <REG_DEAD>: If the register is set
	in I2 as well, just lose it.

From-SVN: r233356